Sun had just emerged from the “cave” of finishing the book’s illustrations. He spent a year completing 180 drawings, pen on vellum, and managed to damage his shoulder in the process. It was his attempt to bring a sensibility reminiscent of some of his favorite writer-illustrators — Bill Watterson of “Calvin and Hobbes,” Shel Silverstein, Maurice Sendak — into the social-media age. In the book, an alien comes to Earth and encounters animals and trees, which he assumes are people.There is an otter that spouts art theory. An egg enduring an existential crisis. A melancholic tree. A bee who offers therapy to a bear. The story lines intersect, vanish, reappear.